Volcano!

The Barren Island volcano, India’s only active volcano erupted recently. The eruption made news and caused scientists to sit up and take notice, making this a good time for us to find out more about volcanoes.

The name given to melted or molten rock is magma. When this reaches Earth’s surface, we call it lava. (Photo courtesy: Hawaii Volcano Observatory (DAS)/Wikipedia)

What’s a volcano?

A volcano is a cone shaped mountain or a hill with a vent or opening at its peak. Through this, melted rock, ash and dust are thrown out when the volcano erupts.

When old magma chambers fill up with new melted rock, that can cause an eruption too.

But why does a volcano erupt? Well, rock deep beneath the Earth sometimes melts, and when it does, it becomes lighter than the solid rock around it. Stuff that’s lighter or less dense (that’s the scientific word!) wants to rise always. So this melted rock starts climbing up looking for ways to reach the surface. And when it does find a vent, a volcanic explosion happens.

Sometimes when you get angry, but keep quiet about it, the anger starts to build up inside you. It builds and builds until you can hold it
no longer and simply explode angrily. That’s how the volcano operates too.

Where are all the volcanoes?

Underwater volcanic eruptions can create islands. In 2005, a volcanic eruption in the Pacific Ocean near Tonga created this island.

Look at the picture below. You can see that the continents are broken up into pieces like a jigsaw puzzle. Those are the borders between plates. As you may know, the surface of the Earth is broken up into massive pieces called plates. The meeting point of two plates makes a boundary.

The red dots are volcanoes. As you can see the most seem to occur along plate boundaries.

Where is the world’s biggest volcano?

As you can probably make out from the image, Tamu Massif has very gentle slopes.

Mauna Loa in Hawaii (part of the United States) is generally believed to be the answer. But in 2013, a gigantic undersea volcano was discovered in the Pacific Ocean east of Japan which is now recognized as the most massive volcano on Earth. Named Tamu Massif, this volcano is as large the Britain! Its top lies about 2000 metres below the ocean’s surface.

Famous volcanic eruptions

The ruins of Pompei with Mount Vesuvius seen in the background.

Among the most famous was the eruption of Mount Vesuvius in Italy in the year 79. The disaster, which released energy equal to 100,000 big bombs, wiped out the town of Pompei. Vesuvius is an active volcano and although it hasn’t erupted since 1944, there is every chance it will in the future.

Ash clouds caused by the eruption of Eyjafjallajökull

More recently, the volcano Eyjafjallajökull in Iceland erupted in 2010, and the ash cloud that was released disturbed flights in Europe for almost a week.

Volcanoes and life

Pacific Sleeper Shark

With all that sound and fury, and ash and dust, you would associate volcanoes with death, not life, right? Wrong! The warmth, minerals and the bacteria found in the sea around an active volcano actually seems to attract small creatures like shrimp, crabs and some kinds of worms!

In one astonishing incident, scientists even found a less-seen species of shark called the Pacific Sleeper Shark swimming around the mouth of an extremely active volcano in the Pacific Ocean.

Islands born of fire

Volcanic eruptions have also created one of the most unusual and wildlife rich habitats on Earth. Take the islands of the Galapagos which are situated close to the Equator off the coast of South America in an area of high volcanic activity.

The Marine Iguana

The islands were formed from materials generated by volcanic eruptions and their distance from land meant that animals here evolved (developed) differently from anywhere else on the planet. As a result, we have unique animals here such as the Galapagos Giant Tortoise, Marine Iguana (the world’s only sea-going lizard) and the Waved Albatross.

In fact the unique development of animals here in response to the environment inspired Charles Darwin to come up with his famous theory of evolution.